In the Guardians of Ga'hoole series, all of the known owl inhabitants of the Middle Kingdom have blue feathers. The owls are recognizable species - Long-eared Owls, Pygmy Owls, etc - but their colouration is made up of different shades of blue. The shades very from owl to owl, some owls being turquoise and others having more cobalt feathers.
The culture of the blue owls appears to be influenced by Hinduism and Chinese beliefs. The concept of phonqua bares similarities to karma, while the concept of zi is comparable to qi.